This website is dedicated to providing public information regarding DePuy Hip recall and other related information to the recall. None of the information on this site is intended to be formal legal or medical advice, nor should any information on this site be construed as advice that should be used in lieu of information from your attorney or physician.

Tuesday, June 11, 2013

Hip Implants: When Innovation Does Not Equate to Improvement

Posted by Cal
WarrinerMonday,
June 10, 2013 4:51 PM ESTLegal Examiner (Palm Beach)[Nice review of the journal summary I just published on the hip revisions with 11 patients after 15 months.]

Modular design hip replacements were first introduced about 30 years ago to
allow surgeons intraoperative flexibility. They were marketed to younger
patients who were presumably more active.
Although there was little data regarding the viability of such designs, that
did not stop the introduction of modular hips into the marketplace and the drive
to “innovate,” as the medical industry likes to call it, when they readily adopt
the latest, greatest and market it as a revolutionary improvement.

A newly published study in the Journal of Bone and
Joint Surgeryfound 11 patients underwent early revisions after
undergoing a total hip arthoplasty with the Stryker modular femoral stem design.
It now appears the additional modular junction creates new opportunities for
corrosion between the neck and the body of the stem.

Since most Stryker Rejuvenate implants used a ceramic ball and polyethylene
socket (ceramic on plastic) both surgeons and patients felt secure in believing
that the metal toxicity issues associated with metal-on-metal ball and socket
designs were not present; however, the Stryker Rejuvenate did in fact have a
significant metal on metal connection. The Rejuvenate design called for the neck
and stem (typically one piece) to be two pieces. To assemble the device, the
modular neck was inserted into the stem. Because both are made of metal, a
significant metal on metal junction resulted.
To increase complications,
the dual taper stems, while allowing for increased options for movement,
create new areas that can potentially corrode, specifically the neck/stem
junction.

The Rejuvenate combined a titanium-molybdenum-zirconium-iron (TMZF) alloy for
the stem with a neck made from cobalt-chromium. In this study, it was just seven
months after implant that most patients began experiencing pain. None of the
patients suffered infections but serum cobalt levels were elevated in the
patients’ blood. Fluids were beginning to collect in tissues and pseudotumors
were seen in all but one patient.These failures mimicked those seen in previously recalled metal on metal hips
even though the articular surfaces were not metal on metal. Instead of a 15-year
life expectancy for a hip replacement, revision surgery took place at 15 months.
And this was difficult surgery necessitating removal of the implant along with
bone and necrotic tissue. Pale green chromium phosphate particles were observed.
The cause of the failure was corrosion of the femoral neck-body junction. Also
the femoral head-neck junction had corrosion though to a lesser degree. When the
authors inspected the tissues surrounding the defective hips microscopically,
the tissue showed dead cells and a high concentration of metal.
What’s ahead for these patients, asks two very prominent New York-based
surgeons? In a commentary that accompanies the published report, the doctors
wonder if patient’s bodies are more susceptible to future corrosion since they
have had complications.

When will the next “innovation” subject patients to new dangerous
“complications”?
After all, these hips were introduced to the market using the FDA’s 510(k)
notification process. To obtain clearance to sell the device, manufacturers
notify the agency that the new product is “substantially equivalent” to another
already on the market. But what if those already on the market are defective?
That doesn’t matter it turns out- a defective and even recalled medical device
can be named as a predicate device. Go figure.

Rep.
Edward Markey tried to stop that from happening with the Sound Devices Act
he introduced into Congress last year. The bill would have given the FDA the
authority to reject medical devices if their predecessors were subject to a
recall or in the process of being recalled. It would also require medical device
manufacturers to explain why their products are different from earlier versions,
to explain the “innovation” as it’s called.

That was defeated. In fact, the bill didn’t get even one vote in
committee.
Instead why not require clinical trials to be conducted before a new
orthopedic implant can be sold to consumers? Sounds like a common sense idea
that injured patients assumed was already happening. They assumed
wrong.